Installation

NOTE The Universal Kit will eliminate the need to measure your spindle. Air-Tight's Universal kit comes with (3)
different inner dimension size shims for the 3500lb. and (1) for the 5200lb and 7000lb. One or none of the shims
may be used in putting on the stainless steel bushing. NOTE : Installation of the Air-Tight Bearing Protector
should only be undertaken by someone familiar with the process of repacking and installing wheel bearings. Seek
professional advice if you have not successfully completed these processes in the past. You may download installation
instructions and view installation videos at Here.

Universal Kit Installation (Use for Universal Kit Installation)
The Universal Kit will eliminate the need to measure your spindle. Air-Tight's Universal Kit comes with (3) different inner dimension size shims. One or none of the shims may be used in putting on the stainless steel bushing. Note: The universal kit for the 5 lug/ 3500lb has 3 shims.
The universal kit for the 6 lug/ 5200 and the 8 lug 7000lb has 1 shim.

One of (2) things will happen:

Air-Tight's stainless steel bushing will fit your spindle snug, without the use of a shim.

One of the (3) shims will fit your spindle snug so Air-Tight's stainless steel bushing can bond directly on top of the shim.

Follow these steps below for putting on the bushing:

1. If there is a stainless steel sleeve on your axle, you must
remove it. Removal can be accomplished by carefully splitting the bushing
in half, using a hammer and a thin tip screwdriver. Exception: If your axle
is made by U.F.P. (Unique Functional Products) (Check your trailer manufacture
with Cross Reference Chart to see if
your mfg. is U.F.P.) the bushing does not have to be removed due to their
bushing is sealed to the spindle. If you are not sure which axle manufacturer
you have, go to our web site, which lists over 70 trailer manufacturers and
the axles they use or match it up to the spindle in the pictures on the Illustrated
Universal Bushing Assembly Sheet.

If the spindle is a drilled spindle, look to see where the
grease hole is located on the spindle. If the grease hole is not on or through
the edge of the bearing journal of the spindle, then to simplify the installation
of the bushing, simply drill into the grease hole with a 3/16 “ drill
bit about 1/4 “ in and open the hole into the bearing journal. This
will eliminate driving the bushing back further on the spindle to leave the
grease hole open. Remove any burrs caused by the drilling with a file prior
to putting on the shim and or bushing. Draw a straight line through the grease
hole to the back of the spindle with a permanent marker. This will mark the
location of the grease hole. Match one of the shims to your spindle. The shim
that fits the closest is the shim you will bond to the spindle.
Note: If Air-Tight's stainless steel bushing fits on the spindle the closest,
the shims are not needed.

Clean any corrosion on the axle with emery cloth and wipe clean
with a degreaser. Clean the inner dimensions of the shim with a degreaser.

Shake up the bonding agent by removing the cap, cut the tip
with a razor knife and screw the cap back on. Squeeze the container a few
times back and forth. This will mix the bonding agent so that it is thick
and consistent and easy to apply. Put the bonding agent 360 degrees on
the axle where the shim will go and 360 degrees on the inner dimensions
of the shim.

Put the shim on the spindle. Even if the shim goes on by hand,
use an old inner bearing and a short pipe or punch and tap on the bearing
until the bearing bottoms out. Remove the bearing. This will form the shim
to the contour of the spindle and put the shim back against the shoulder.
The shim will block the grease hole on the spindle. Use an awl or a nail to
pierce through the shim where you marked the hole, leaving the grease hole
open.

Bond Air-Tight's stainless steel bushing on the top of the
shim the same way you put on the shim. If you had to press on the bushing
with an old bearing, when the bearing bottoms out, remove the bearing and
use a brass or aluminum punch to place the bushing in against the shoulder.
Tap on the taper of the bushing on both sides until the bushing is against
the shoulder If there is no shoulder, tap the bushing about 1/16 of an inch
in from the inner bearing. Air-Tight's stainless steel bushing should always
be about 1/16 of an inch back from the inner bearing when placed properly.

Be sure to remove any debris in the grease hole. Removal of
the debris can be done by greasing the zerk fitting and letting the grease
clean out the hole.

When the bushings are assembled, discard the remaining shims
and continue with the main directions.

Disclaimer: The Universal Kit fits most axle manufacturer sizes. If your axle
size is not covered by the Universal Kit. Contact Air-Tight to exchange
the bushing for your particular size.

Shake up the bonding agent by removing the cap,
cut the tip with a razor knife and screw the cap back on. Squeeze
the container a few times back and forth. This will mix the bonding
agent so that it is thick and consistent and easy to apply.

Put the bonding agent 360 degrees on the axle where
the bushing goes and 360 degrees on the inner dimensions of the
bushing.

Put the bushing on the axle with the taper towards
the outside. Bushings may go on by hand or you may have to tap
the bushing on with an old inner bearing and a short pipe.

Tap the bushing on the axle against the shoulder.
If there is no shoulder, tap the bushing on where the seal will
ride 100% on the surface.

Indicating where the old seal was riding is the
best way of placing the bushing. The rule of thumb is about 1/8
of an inch in from the inner bearing. That will leave open the
grease hole if the axle is a drilled spindle.

If the bushing has to be driven on with an old bearing, then
once the bearing bottoms out on the spindle, remove the bearing and use a
brass or aluminum punch to place the bushing in that 1/16 of an inch. You
want to tap on the taper part of the bushing.

If the axle has a "Sure Lube" system, which has
a hole drilled through the back of the spindle, the hole has to
be drilled and tapped to 1/8 inch N.P.T.

If there are any obstructions to drilling and
tapping the hole, simply use a die grinder and remove the obstruction.

Use cold galvanized spray to touch up any bare
metal.

Once tapped, grease can be pumped through the
hole where the seal rides to back flush the old grease and metal
shavings out of the back of the spindle.

Once flushed, put Teflon tape on the zerk fitting
and tighten.

We use a sealable zerk fitting to hold back the
air pressure 100%. Part Z-100.

If the spindle is drilled, put the inner bearing
in the hub dry. Clean the hub where the seal is pressed in with
a degreaser and apply bonding agent 360 degrees on the hubs inner
dimensions and apply bonding agent 360 degrees on the seal's outer
dimensions.

Press the seal into the hub flush with the hub.
Make sure the seal is started evenly, about 1/8 of an inch into
the hub before it is driven in all the way. You should use a seal
driver or press for putting in the seals. It is important to note
that the seals tend to start in the hub unevenly. Tap on the seal
driver just to start the seal and then tap on the high end of
the seal driver to get the seal started evenly. Once the seal
is started evenly, drive the seal in flush with the hub. That
will place the seal 100% on the bushing and true the seal with
the hub.

If the spindle is not drilled, put the inner bearing
into the hub packed with grease. Wipe out any grease that is on
the inner dimensions of the hub where the seal is pressed in.
Clean the surface with a degreaser until it is completely clean
of all grease. Next, apply bonding agent to the hub I.D. and the
seal O.D. Press in the seal until the seal is flush. Make sure
to press in the seal evenly. Wipe off excess bonding agent, and
pack the cavity between the seal and the inner bearing with grease.
Make sure the cavity is full. Next, pack grease into the middle
of the hub, between the two races.

Let the entire assembly cure for 24 hours before
submerging it in water, in order to allow for proper setup of
the bonding agent.

On the Commercial model, when the bonding agent
is cured, use a manual air pump such as a bicycle pump and put
in 15 pounds. Remove the pump and bleed the valve stem until the
gauge reads 10 p.s.i.

After the initial trip you may have to pump the
hub back up to 10 p.s.i due to the air pockets in the grease equalizing
to the 10 p.s.i. Put grease on the valve stem and replace the
valve stem cap. Replace the valve stem cap.

DO NOT PRESSURIZE OVER 30
PSI!!

On the Sport Model, use a manual pump with a sports
needle, put grease on the sport needle and insert it into the
center of the diaphragm. Pump up until the ridges in the diaphragm
protrude outwards.

Diaphragm should protrude out past the cap approximately
3/4 of an inch. That will pressurize the hub with approximately
5 to 10 psi.

DO NOT OVER PRESSURIZE THE
DIAPHRAGM!!

Your indicator of a pressurized hub is by visually
seeing where the diaphragm position is relative to the face of
the cap.

For example, if the diaphragm protrudes out greater
than 1 inch, the V's between the rings on the diaphragm will begin
to flatten out and the pressure will be greater than 10 psi.

So, ideally, the diaphragm should be inflated
approximately 3/4 of an inch past the cap.

If the diaphragm's rings and face are compressed
against the cap, it is time to pump the diaphragm out to approximately
3/4 of an inch.

Remember; lubricate the sport needle with grease
whenever you inflate the diaphragm.

Note: Release the air in the diaphragm through the sport needle prior to removing the diaphragm for regreasing.

Your Air-Tight Bearing Protector will protect the grease and let the grease do its job. And I think you will agree, it's not only easy to install, it's simply the best bearing protection of it's kind available.

Your Air-Tight hub kit is designed to last a long
time. The wear parts are the seal and eventually the bushing,
depending on the severity of the environment and mileage. In the
meantime, with proper installation, you should experience thousands
of miles out of each seal. When air pressure can no longer be
maintained you will see a loss of air pressure on the gauge.

Air-Tight tells you when it's time to change seals
and repack bearings. If pressure is equal to or less than 5 p.s.i.,
add pressure to 10 p.s.i.. At the end of the seal life, there
will be a gradual increase in air pressure leakage out of the
hub. When you can no longer hold air pressure statically, this
means that it's time to change the seal and repack the bearings.
If you discover this loss of air pressure while on a trip, air
up the hubs (using a bicycle pump do not use a motorized/auto
air pump) to 10 p.s.i. before submerging in water.

The Air-Tight gauge will warn you of potential
problems prior to hub failure. During a trip while stopping for
fuel or launching a boat at a ramp, quickly check the pressure
gauges. If the p.s.i. on departure was 10 p.s.i., you should experience
a pressure increase of 1-1.5 p.s.i. in normal conditions due to
the heat buildup. If a gauge is abnormally higher (3 p.s.i. or
greater), there may be a brake dragging or a future bearing problem
creating extra heat.

Maximize your seal's life. Do not over pressurize
the hub (never inflate to 30 p.s.i. or greater). Ideal pressure
for protection and maximum life of the seal is 10 p.s.i. Do not
use a motorized or auto tire pump to pressurize the Air-Tight
Bearing Protector. Use a hand powered bicycle type pump for the
minimal amount of air you will need.WARNING: OVER-PRESSURING HUB
CAN LEAD TO GAUGE BREAKAGE

Temperature change will also change pressure.
Colder air temperature will lower the p.s.i. slightly and hotter
temperatures will increase the p.s.i. slightly. In a short time,
you will know what your pressure will run in a given situation,
depending on trip duration, ambient temperature, and your typical
environment.

You will enjoy the ability to monitor what is
going on inside your hubs at all times. The purpose of this product
is to eliminate time spent on the roadside doing time intensive
and unnecessary repairs. Consider it insurance for your investment!

Air Tight recommends changing the seal and re-packing
bearings when the seal no longer statically can hold pressure.

Loosen cap slightly, tap on cap 360 degrees around with
rubber mallet or soft faced tool until adapter ring comes off.
(Removal of adapter ring is only necessary when removing hub for
repacking and seal change.)

When you can no longer statically hold air pressure
in your hubs , Air-Tight recommends that you repack your bearings
and change your seal.

Trailers operating under extreme conditions can
add grease to the bearings after 1 year. Do this by releasing
the air pressure in the cap and unscrewing the cap off the adaptor.
Note: (If the cap is tight, use a rubber strap filter wrench to
loosen). On the axle where the zerk fitting was removed, screw
in a zerk fitting if the spindle was tapped or place a zerk fitting
on the end of a grease gun and press the fitting by hand against
the hole in the axle. Add grease until the new grease comes through
the outer bearing. Wipe off excess grease. Remove the zerk fitting.
Replace the cap and add 10 psi. Extreme conditions mean : High
mileage annually and running a trailer load near total gross vehicle
weight rating.

If the hub has a tang washer, our 1 1/2" special
socket can take the hub off without a removal of the adaptor ring.

If the axle has a cotter pin, you must remove
the adaptor ring to pull out the cotter pin. When finished, the
adaptor ring can be bonded back in with a green retaining compound
such as locktight. Again, make sure the surface is clean before
using the bonding agent.

Disconnect the trailer wire harness from the truck when submerging
your trailer. This will eliminate hot light bulbs going into cool
water and electrolysis coming from the 12 volts which can attack
your trailer in salt water.